Impression fabric made of yarn containing variable shrinkage filaments

ABSTRACT

Woven impression fabric for use in a printing machine and having improved ink retention and ink metering characteristics, said fabric being woven with filling yarns of composite synthetic continuous filament yarns in which at least two sets of filaments possess differential shrinkage characteristics, said yarns being uniformly textured along their length due to the shrinkage of at least one of the sets of filaments.

atent 11 1 Leach 1451 July 31, 1973 [54] IMPRESSION FABRIC MADE OF YARN 3,199,281 8/1965 Maerov et al. 57/140 BY CONTAINING VARABLE SHRINKAGE 2,918,160 12/1959 Thompson 197/172 FILAMENTS 3,350,871 11/1967 Plerce et al 28/72.]7 X 3,423,809 l/l969 Schmm 57/157 F X [75] Inventor: Jack Leach, Greensboro, N.C. 3,444,681 5/1969 Reese 57/157 R X [73] Asslgnee' gtzgz gzi gf g Primary Examiner-Ernest T. Wright, Jr.

Attorney-Cushman, Darby & Cushman [22] Filed: Feb. 16, 1971 1211 Appl. No.: 115,761 [57] ABSTRACT Woven impression fabric for use in a printing machine 521 US. (:1. 197 172 and having improved ink retention and ink metering [51] Int. Cl B413 31/02 characteristics, Said fabric being Woven with filling [58] Field of Search 197/172; 57 140, y of composite synthetic continuous filament y 57 140 Y 157 R, 157 2 72 17 in which at least two sets of filaments possess differential shrinkage characteristics, said yarns being uni- [56] References Cited formly textured along their length due to the shrinkage UNITED STATES PATENTS of at least one of the sets of filaments.

5 Claims, No Drawings IMPRESSION FABRIC MADE OF YARN CONTAINING VARIABLE SHRINKAGE F ILAMENTS This invention relates to woven impression fabrics, such as typewriter ribbon fabrics and the like, and in particular to fabrics of this type having improved ink capacity and ink metering characteristics.

The use of fabrics as carriers for ink in printing mechanisms such as typewriters, calculators and computers is common practice. Over a long period of time the production of fabrics for this purpose has become more sophisticated and has advanced from the use of natural fibers to synthetic fibers and films as the writing requirements for this carrier have become more and more difficult to attain. ln the early stages of this art the use of natural fibers such as cotton and silk permitted the absorption and holding of relatively large amounts of ink because they were naturally absorptive and relatively thick. The high carrying capacity of the fabrics were an advantage although their thickness did not allow the sharp, clear write that is currently required nor did it permit the efficient use of the ink with which the fabrics were impregnated. Later developments in nylon fabrics permitted much thinner fabrics to be used, but the amount of ink that was storable in the relatively thin fabrics was limited and the metering capabilities of these fabrics were also somewhat limited.

The development of techniques for making better inks and inking machinery have increased the inherent capabilities of conventional typewriter ribbon fabric but not to the extent desired.

More recent developments in the manufacture of fabrics for this end use have included techniques which permit intra-fiber bundle distortion of the continuous filament construction of the yarns used to make the fabrics and have resulted in somewhat greater storage capacity within the fabric as well as somewhat better metering capabilities of the finished and inked fabric. The problem lies in the fact that the methods for bringing about this filament distortion are expensive and somewhat unpredictable. Full utilization of the texturing within the fiber bundles has not been possible because of the extremely high constructions, such as 260 to 350 square, generally used in the manufacture of fabrics of this type.

There is therefore a need to create a higher absorption of ink, greater ink storage capacity and improved ink metering characteristics in fabric for typewriter ribbons and the like.

The present invention provides improved ink absorption, retention and metering by constructing the typewriter ribbon fabric of certain composite continuous synthetic filament yarns which exhibit differential shrinkage between at least two sets of filaments within each yarn and which possess a natural ability to absorb ink and hold it for improved metering. Composite yarns of the differential shrinkage type are known to exhibit distortion or bulking when shrinkage of one of the sets of filaments is effected. By utilizing this variability of shrinkage it has been found possible to achieve the filament distortion that heretofore has been achieved by texturing, but without the variability of distortion that is normally inherent in texturizing processes. That is, by carefully controlling the shrinkage, the distortion along the length of each yarn and the distortion as between different yarns can be made highly uniform. As a result a fabric is obtained which is highly uniform in its ink absorbing, retaining and metering characteristics. It should be noted that the shrinking power of bicomponent yarns is much stronger than that of texturized yarn. Bicomponents have variable heat sensitivity together with higher contracting power which allows the distortion to form even under relatively high restraint caused by densely packing the yarns for smooth surface effects.

The fabric of the present invention also exhibits the necessary characteristics of thinness, smooth flat surface and durability which are required of an impression fabric.

A particularly preferred yarn is nylon 472 (E. l. du Ponts Qiana). This yarn is silk-like in appearance and has high wicking characteristics, similar to those of cotton, and excellent abrasion resistant properties. The smooth surface of the yarn together with the internal distortions of the filaments give greater ink storage capacity to the typewriter ribbon while preserving the smooth, even surface of the fabric to give good write and at the same time effect better metering of the ink during printing because the capillary action will not be impeded or adversely affected by the filament distortion within the fiber bundle.

It should be noted that this type of variable shrinkage fiber bundle has been produced with other combinations of yarns within the single fiber and by the extrusion of two different polymers through a single spinneret to result in two different polymers within the single fiber bundle with those polymersdemonstrating variability in both physical and shrinkage characteristics which would result in the type of filament distortion referred to above. An example of this is a fiber produced by the Allied Chemical Company, under the name of Source which contained elements of polyester and polyamide within the same fiber bundle and resulted in a variable shrinkage characteristic whichis utilizable to bring about the above described effects.

Other types of yarn suitable for this invention are those described in U.S. Pat. Nos. 3,199,28 l 3,350,871, 3,423,809 and 3,444,681.

The special yarns may be employed as the filling yarns only or as both filling and warp. When only the filling yarns are the special yarns, the warp yarns may be, for example, nylon 6 or nylon 6.6.

EXAMPLES I AND ll A woven fabric was prepared having a finished construction of 172 ends of 34 filament conventional nylon with a pickage of 117 picks of 60 denier 36 filament Qiana. A similar fabric was prepared with the same nylon construction and with a pickage of 119 picks of 30 denier l8 filament Qiana. Both fabrics exhibited excellent ink absorption and ink metering after impregnation with a commercially available typewriter ink composition.

EXAMPLES AND lV Two woven fabrics were prepared using 30 denier l8 filament Qiana as the warp yarn. in one fabric 30 denier l8 filament Qiana was used as filling and in the other fabric 60 denier 36 filament Qiana was used as filling. Both fabrics exhibited a flat smooth surface and excellent ink absorption and ink metering.

What is claimed is:

1. A woven inked impression fabric for use in a printing machine and having improved ink retention and ink metering characteristics, said inked fabric being woven with filling yarns of composite synthetic continuous filament yarns in which at least two sets of filaments possess differential shrinkage characteristics, said yarns being uniformly textured along their length due to the shrinkage of at least one of the sets of filaments.

2. Fabric as in claim 1 wherein said composite yarns are composed of nylon 472.

3. Fabric as in claim 1 including warp yarns which are continuous filament yarns made of a material selected from the group consisting of nylon 6 and nylon 6.6.

4. Fabric as in claim 1 including warp yarns which have the same composite construction as the filling yarns. 

2. Fabric as in claim 1 wherein said composite yarns are composed of nylon
 472. 3. Fabric as in claim 1 including warp yarns which are continuous filament yarns made of a material selected from the group consisting of nylon 6 and nylon 6.6.
 4. Fabric as in claim 1 including warp yarns which have the same composite construction as the filling yarns.
 5. A method of making impression fabric for use in a printing machine comprising: weaving a fabric from composite synthetic continuous filament yarns, in which yarns at least two sets of filaments possess differential heat-shrinkage characteristics; heat-treating the fabric to impart uniform texturing along the length of the yarns; and impregnating the fabric with ink. 